Hydrophobically modified Ethoxylated Urethane Copolymers (HEUR) are blended as a water-soluble thickener having excellent viscosity stabilizing property and suitable texture in cosmetic compositions and the like (see, e.g., Patent Document 1). Compositions thickened with a hydrophobically modified ethoxylated urethane (also referred to as “hydrophobically modified polyether urethane”) provide a unique jiggling touch and are attractive as cosmetic base compositions to be applied to skin and the like.
Such compositions are, however, characteristically difficult to cause change in the viscosity due to the concentration of a salt to be co-blended or pH variation of the compositions, but have a problem of reduction in the viscosity when stored at a high temperature (e.g., 50° C.). Patent Document 1 suggests that addition of a water-soluble polymer such as carboxyl vinyl polymers and xanthan gum in addition to hydrophobically modified ethoxylated urethane can prevent reduction in the viscosity at high temperatures.
Patent Documents 2 and 3 describe that a combination of hydrophobically modified ethoxylated urethane with a microgel of a thickener can provide a synergistic thickening effect. In Patent Document 2, a microgel obtained by grinding a gel formed from a hydrophilic compound having a gelling ability such as agar and gellan gum is blended. In Patent Document 3, a microgel obtained by dissolving water-soluble ethylenically unsaturated monomers (specifically, dimethylacrylamide and 2-acrylamido-2-methylpropane sulphonate) in a dispersed phase and radically polymerizing the monomers in the dispersed phase is blended.
However, in the case of co-blending the water-soluble polymer described in Patent Document 1 or the microgels of a thickener described in Patent Documents 2 and 3 in a composition containing hydrophobically modified ethoxylated urethane, improved high-temperature stability and a synergistic thickening effect can be obtained, but mixing a third component such as an oily component or an amphiphile may remove a jiggling unique feeling originally possessed by the composition thickened with the hydrophobically modified ethoxylated urethane.